linux-dev/arch/x86/boot/header.S, branch linus/master

efi: x86: Fix config name for setting the NX-compatibility flag in the PE header

2022-06-01T12:07:48Z

Commit 21b68da7bf4a ("efi: x86: Set the NX-compatibility flag in the PE header") intends to set the compatibility flag, i.e., IMAGE_DLL_CHARACTERISTICS_NX_COMPAT, but this ifdef is actually dead as the CONFIG_DXE_MEM_ATTRIBUTES Kconfig option does not exist. The config is actually called EFI_DXE_MEM_ATTRIBUTES. Adjust the ifdef to use the intended config name. The issue was identified with ./scripts/checkkconfigsymbols.py. Fixes: 21b68da7bf4a ("efi: x86: Set the NX-compatibility flag in the PE header") Signed-off-by: Lukas Bulwahn Link: https://lore.kernel.org/r/20220601115043.7678-1-lukas.bulwahn@gmail.com Signed-off-by: Ard Biesheuvel

efi: x86: Set the NX-compatibility flag in the PE header

2022-05-03T13:31:28Z

Following Baskov Evgeniy's "Handle UEFI NX-restricted page tables" patches, it's safe to set this compatibility flag to let loaders know they don't need to make special accommodations for kernel to load if pre-boot NX is enabled. Signed-off-by: Peter Jones Link: https://lore.kernel.org/all/20220329184743.798513-1-pjones@redhat.com/ Signed-off-by: Ard Biesheuvel

x86: Bump ZO_z_extra_bytes margin for zstd

2020-07-31T09:49:08Z

Bump the ZO_z_extra_bytes margin for zstd. Zstd needs 3 bytes per 128 KB, and has a 22 byte fixed overhead. Zstd needs to maintain 128 KB of space at all times, since that is the maximum block size. See the comments regarding in-place decompression added in lib/decompress_unzstd.c for details. The existing code is written so that all the compression algorithms use the same ZO_z_extra_bytes. It is taken to be the maximum of the growth rate plus the maximum fixed overhead. The comments just above this diff state that: Signed-off-by: Nick Terrell Signed-off-by: Ingo Molnar Tested-by: Sedat Dilek Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20200730190841.2071656-6-nickrterrell@gmail.com

efi/x86: Add kernel preferred address to PE header

2020-03-08T08:58:20Z

Store the kernel's link address as ImageBase in the PE header. Note that the PE specification requires the ImageBase to be 64k aligned. The preferred address should almost always satisfy that, except for 32-bit kernel if the configuration has been customized. Signed-off-by: Arvind Sankar Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200303221205.4048668-4-nivedita@alum.mit.edu Link: https://lore.kernel.org/r/20200308080859.21568-18-ardb@kernel.org

efi/libstub: Introduce symbolic constants for the stub major/minor version

2020-02-23T20:59:42Z

Now that we have added new ways to load the initrd or the mixed mode kernel, we will also need a way to tell the loader about this. Add symbolic constants for the PE/COFF major/minor version numbers (which fortunately have always been 0x0 for all architectures), so that we can bump them later to document the capabilities of the stub. Signed-off-by: Ard Biesheuvel

efi/x86: Use symbolic constants in PE header instead of bare numbers

2020-02-23T20:59:42Z

Replace bare numbers in the PE/COFF header structure with symbolic constants so they become self documenting. Signed-off-by: Ard Biesheuvel

efi/x86: Add true mixed mode entry point into .compat section

2020-02-23T20:59:42Z

Currently, mixed mode is closely tied to the EFI handover protocol and relies on intimate knowledge of the bootparams structure, setup header etc, all of which are rather byzantine and entirely specific to x86. Even though no other EFI supported architectures are currently known that could support something like mixed mode, it still makes sense to abstract a bit from this, and make it part of a generic Linux on EFI boot protocol. To that end, add a .compat section to the mixed mode binary, and populate it with the PE machine type and entry point address, allowing firmware implementations to match it to their native machine type, and invoke non-native binaries using a secondary entry point. Signed-off-by: Ard Biesheuvel

efi/x86: Drop redundant .bss section

2020-02-23T20:59:42Z

In commit c7fb93ec51d462ec ("x86/efi: Include a .bss section within the PE/COFF headers") we added a separate .bss section to the PE/COFF header of the compressed kernel describing the static memory footprint of the decompressor, to ensure that it has enough headroom to decompress itself. We can achieve the exact same result by increasing the virtual size of the .text section, without changing the raw size, which, as per the PE/COFF specification, requires the loader to zero initialize the delta. Doing so frees up a slot in the section table, which we will use later to describe the mixed mode entrypoint. Signed-off-by: Ard Biesheuvel

x86/boot: Introduce setup_indirect

2019-11-12T15:21:15Z

The setup_data is a bit awkward to use for extremely large data objects, both because the setup_data header has to be adjacent to the data object and because it has a 32-bit length field. However, it is important that intermediate stages of the boot process have a way to identify which chunks of memory are occupied by kernel data. Thus introduce an uniform way to specify such indirect data as setup_indirect struct and SETUP_INDIRECT type. And finally bump setup_header version in arch/x86/boot/header.S. Suggested-by: H. Peter Anvin (Intel) Signed-off-by: Daniel Kiper Signed-off-by: Borislav Petkov Reviewed-by: Ross Philipson Reviewed-by: H. Peter Anvin (Intel) Acked-by: Konrad Rzeszutek Wilk Cc: Andy Lutomirski Cc: ard.biesheuvel@linaro.org Cc: Boris Ostrovsky Cc: dave.hansen@linux.intel.com Cc: eric.snowberg@oracle.com Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Juergen Gross Cc: kanth.ghatraju@oracle.com Cc: linux-doc@vger.kernel.org Cc: linux-efi Cc: Peter Zijlstra Cc: rdunlap@infradead.org Cc: ross.philipson@oracle.com Cc: Thomas Gleixner Cc: x86-ml Cc: xen-devel@lists.xenproject.org Link: https://lkml.kernel.org/r/20191112134640.16035-4-daniel.kiper@oracle.com

x86/boot: Introduce kernel_info

2019-11-12T15:10:34Z

The relationships between the headers are analogous to the various data sections: setup_header = .data boot_params/setup_data = .bss What is missing from the above list? That's right: kernel_info = .rodata We have been (ab)using .data for things that could go into .rodata or .bss for a long time, for lack of alternatives and -- especially early on -- inertia. Also, the BIOS stub is responsible for creating boot_params, so it isn't available to a BIOS-based loader (setup_data is, though). setup_header is permanently limited to 144 bytes due to the reach of the 2-byte jump field, which doubles as a length field for the structure, combined with the size of the "hole" in struct boot_params that a protected-mode loader or the BIOS stub has to copy it into. It is currently 119 bytes long, which leaves us with 25 very precious bytes. This isn't something that can be fixed without revising the boot protocol entirely, breaking backwards compatibility. boot_params proper is limited to 4096 bytes, but can be arbitrarily extended by adding setup_data entries. It cannot be used to communicate properties of the kernel image, because it is .bss and has no image-provided content. kernel_info solves this by providing an extensible place for information about the kernel image. It is readonly, because the kernel cannot rely on a bootloader copying its contents anywhere, but that is OK; if it becomes necessary it can still contain data items that an enabled bootloader would be expected to copy into a setup_data chunk. Do not bump setup_header version in arch/x86/boot/header.S because it will be followed by additional changes coming into the Linux/x86 boot protocol. Suggested-by: H. Peter Anvin (Intel) Signed-off-by: Daniel Kiper Signed-off-by: Borislav Petkov Reviewed-by: Konrad Rzeszutek Wilk Reviewed-by: Ross Philipson Reviewed-by: H. Peter Anvin (Intel) Cc: Andy Lutomirski Cc: ard.biesheuvel@linaro.org Cc: Boris Ostrovsky Cc: dave.hansen@linux.intel.com Cc: eric.snowberg@oracle.com Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Juergen Gross Cc: kanth.ghatraju@oracle.com Cc: linux-doc@vger.kernel.org Cc: linux-efi Cc: Peter Zijlstra Cc: rdunlap@infradead.org Cc: ross.philipson@oracle.com Cc: Thomas Gleixner Cc: x86-ml Cc: xen-devel@lists.xenproject.org Link: https://lkml.kernel.org/r/20191112134640.16035-2-daniel.kiper@oracle.com